A self servo write method is disclosed in International Publication No. WO96/28814 (corresponding to Japanese Patent Laid-Open No. Hei10-504128) as a method adopted in a conventional magnetic disk apparatus. This method adopts a technique of setting a gap between servo tracks on which data is recorded. In accordance with this self servo write method, the magnetic disk apparatus itself records a pattern by using a head provided therein and sets a pitch of the head movement by using the amplitude of a signal for generating this pattern as a base.
In the conventional magnetic disk apparatus, however, the width of a recording/reproducing device of the head provided for the magnetic disk apparatus exhibits hard variations even if the amplitude of a reproduction signal is set at a uniform level. These hard variations exhibited by the recording/reproducing device of the head cause gap variations in actual servo tracks of the magnetic disk apparatus. In turn, these variations in gap cause the number of servo tracks written onto magnetic disk surfaces to vary even if the surfaces have the same size. Thus, the conventional magnetic disk apparatus has a problem that it is impossible to verify whether required servo tracks have been written, that is, whether a servo signal has been recorded successfully, before verification of the number of servo tracks after the operation to record the servo signal onto the entire surface of the magnetic disk. Particularly, in the case of tracks laid out at pitch smaller than a track width by several hundreds of nm as is the case with a contemporary magnetic disk apparatus, the effect of dimensional variations of the recording/reproducing device is bigger. Thus, the number of operations to rerecord the servo signal increases. As a result, there is raised a problem that the throughput for an operation to record a servo signal decreases considerably.
It is thus an object of the present invention addressing the problems described above to provide a magnetic disk apparatus capable of writing a servo signal without using an external write apparatus and capable of recording a predetermined servo signal onto the surface of a magnetic disk with a high degree of reliability and a high degree of efficiency even if dimensional variations of a recording/reproducing device of a head exist, and provide a servo signal recording method adopted by the magnetic disk apparatus.